Short answer: it depends. There are "pay as you go" plans that do not require a contract, but you'll need to know whether your phone will work with those SIM cards. I had an unlocked phone that I purchased and was able to use in Jordan (with Orange) and then in the US with AT&T. As long as your phone is not carrier locked, and the GSM frequencies it uses are also used in the US, you should be able to find something that works.
Another possibility would be to get a cheap "pay as you go" phone from any discount store, use it, then leave it behind (or just pack it away for a future visit) when you're done. It won't be a Blackberry, but at least it will do phone and text and you'll have a US number while visiting.
Short answer: it depends. There are "pay as you go" plans that do not require a contract, but you'll need to know whether your phone will work with those SIM cards. I had an unlocked phone that I purchased and was able to use in Jordan (with Orange) and then in the US with AT&T. As long as your phone is not carrier locked, and the GSM frequencies it uses are also used in the US, you should be able to find something that works.
Another possibility would be to get a cheap "pay as you go" phone from any discount store, use it, then leave it behind (or just pack it away for a future visit) when you're done. It won't be a Blackberry, but at least it will do phone and text and you'll have a US number while visiting.